铁路新型加筋土挡墙抗震性能数值模拟

Numerical Simulation on Seismic Performance of a New Type of Reinforced Soil Retaining Wall for Railways

中国铁路建设逐渐向多震地区延伸,为了提高加筋土挡墙地震服役期,各类支档结构的抗震性能成为研究热点。通过Flac 3D数值模拟软件构建铁路新型加筋土挡墙足尺模型的方法,同传统模块式加筋土挡墙进行对比,分析了新型加筋土挡墙的抗震性能。结果表明:在地震作用下,新型加筋土挡墙整体变形趋势为外倾,即面板处水平残余位移随墙高线性增加,最大水平位移发生在墙顶处;加速度放大系数墙面板处>加筋体中部区>加筋体后填土区,挡墙中下部整体性较好,而中上部不同形式加筋土挡墙存有差异;挡墙墙背水平动土压力沿墙高“先增后减,再增再减”,墙体下部产生一突变点即最大值点;每层筋材应变分布呈“单峰状”,参与抗拔的筋材分布较为均匀,所形成的破裂面形式接近“0.3 H”法理论破裂面(H为墙高)。数值模拟结论可为新型加筋土挡墙抗震机理的研究提供参考和借鉴。

China s railway construction is gradually extending to earthquake prone areas.In order to improve the seismic service life of reinforced soil retaining walls,the seismic performance of various support structures has become a research hotspot.The method of building a full scale model of a new reinforced soil retaining wall for railway by using Flac 3D numerical simulation software was compared with the traditional modular reinforced soil retaining wall,and the seismic performance of the new reinforced soil retaining wall was analyzed.The results show that under earthquake action,the overall deformation trend of the new reinforced soil retaining wall is outward tilt,that is,the horizontal residual displacement at the panel increases linearly with the wall height,and the maximum horizontal displacement occurs at the top of the wall.The acceleration amplification coefficient at the wall panel>the middle area of the reinforced body>the filled soil area after the reinforced body.The overall integrity of the middle and lower parts of the retaining wall is good,while there are differences in the different forms of reinforced soil retaining walls in the middle and upper parts.The horizontal dynamic soil pressure on the back of the retaining wall increases and then decreases along the wall height,and then increases and then decreases,resulting in a sudden change point at the lower part of the wall,which is the maximum value point.The strain distribution of each layer of reinforcement material shows a single peak shape,and the distribution of reinforcement materials participating in the pull-out resistance is relatively uniform,forming a fracture surface form close to the theoretical fracture surface of the“0.3 H”method,and H is the height of the wall.The numerical simulation conclusions can provide reference and guidance for the research on the seismic mechanism of new reinforced soil retaining walls.